The present invention relates to an arrangement of a light wave conductor-phase sensor for measuring minute elongations, wherein a source of polarized light is coupled to one end of the sensor-light wave conductor (polarization preserving, doubly refracting monomer-light wave conductor) and a change in the phase difference resulting from the change in length of the light wave conductor-sensor is detected. In principle, the arrangement of this invention consists of the following series connected component parts: a polarized light emitter, transmission light wave conductor, light wave conductor-phase sensor (or subassembly containing the sensor-light wave conductor), another transmission light wave conduit, light receiver and an electronic measuring or evaluation device, according to U.S. patent application Ser. No. 116,032, the entire disclosure of which is incorporated herein by reference.
With a measuring device of this kind deformations in the range of micrometers can be detected. As a light wave conductor-phase sensor the following subassembly of a series connected components has been used: a polarizer, a coupling, a polarization preserving, doubly refracting mono-mode light wave conductor (or sensor-light wave conductor) and an analyzer. In the prior art light wave conductor-sensor the linearly polarized light is coupled in and a change in the phase difference occurring due to a change in length of the sensor-light wave conductor is detected by a light receiver and evaluated by a subsequent electronic measuring circuit. However, it is desirable to further improve the determination of the measuring values.
For example, the connection between light wave conductor LWC-phase sensors arranged in breaking susceptible zones of a structure, and a measuring device arranged in a control room has been made by transmission light wave conductors when specific properties of light wave conduits such as insensitivity to electromagnetic interference fields, to strong electrical fields and to corrosive or explosive environment are desirable. Nevertheless, still other types of connections and conduits may be desired.